羌塘盆地变形构造与油气聚集保存关系

西藏羌塘盆地地表出露不同层位的地面背斜构造达235个，以侏罗系背斜为主。通过物探及地面地质调查，结合区域构造应力场，进行时空及构造组合分析，可将这些背斜划分为单一型、联合型、复合型和扭动型4种构造组合类型，不同的构造类型分布于盆地的不同部位，主要形成于燕山晚期（J2-K3）及喜马拉雅期变形阶段，且与盆地烃源岩两次生烃时期相匹配，为油气聚集提供了良好条件。目前普遍认为青藏高原新构造运动是造成油气藏破坏最重要的因素，但从断裂构造性质、有效盖层分布以及高原隆升对油气保存的影响分析来看，羌塘盆地断裂以压性断裂为主，内部结构稳定，主要目的层保存完好，勘探前景比较乐观。图4参10

Relationship between deformation structure and petroleum accumulation and preservation, Qiangtang Basin, Tibet

There are about 235 outcropped anticlines in Qiangtang Basin, Tibet, which are dominantly of Jurassic age. Based on geophysical exploration, surface geologic survey, and regional tectonic stress, these anticlines can be classified into four types, viz., simple structure, united structure, complex structure and twisted structure. These four-type structures are distributed in different places in the basin and are mainly formed in the two deformation phases of late Yanshan movement and Himalayan movement. The two phases match with the two periods of hydrocarbon generation, so the structures provide good conditions for hydrocarbon accumulation. The new tectonic movement of Qinghai-Tibet plateau is generally thought as the important factor causing reservoir damage. However, the analysis of fault nature, effective seal rock distribution and plateau uplifting indicates that the faults in the basin are mainly compressive, the internal structure is stable, and the intervals of interest are well preserved and have a good exploratory potential.